Appendix B: The Chilled Water System Optimizer Commissioning view of the Properties page
Chilled Water System Optimizer v2
CARRIER CORPORATION ©2019
Installation and Start-up Guide
85
All rights reserved
Point Name/Description
Range
System Response time in minutes (3=min to 30=max): __ minutes
The response
time period of the building to react to each reset temperature change. If set to less
than the actual system response time, then the reset could search and not be
accurate.
Current interval time is: __:__ minutes and _.__ seconds. — Displays values.
CAUTION
Critical setting.
You set the time it takes for the condenser water system to respond after the
optimization program resets the temperature. The program must perceive if the
system is using less energy after the setpoint has changed and after the system
has settled to the new setpoint.
The following occur during the response time:
Condenser water temperature reaches the new temperature
Cooling tower fans stabilize
Pumps reach their new speed
The response time is difficult to approximate. If you have access to the entire
system, you can trend various points to approximate time.
NOTES
Remote towers (for example, if they are on the roof) response time may be between
5 and 10 minutes.
Towers next to the mechanical room may be between 3 and 5 minutes.
D:
R:
8 minutes
3 to 30 minutes
Minimum and Maximum Reset Increments & Algorithm Reset Gain
Each response period, the program determines the next reset signal that lowers energy
demand most effectively. The program outputs a reset signal between 0 and 10 (deg) (0
(deg) = no reset or warmest condenser water temperature, 10 (deg) = the maximum or
coolest temperature).
EXAMPLE
The program is producing a 5.4 (deg) reset signal. The next time it resets, in
order to minimize energy use, it either adds to the signal, by lowering the condenser
water temperature, or subtracts from the signal, by raising the temperature. Each reset
increment falls between the allowed minimum and maximum.
The actual reset value is based on the reset gains and measurements of the curve
profile. If the program is currently producing a 5.4 (deg) reset, and the next reset
increment is determined to be 1.1 (deg), then the next reset output will be (5.4 (deg) +
1.1 (deg)) = 6.5 (deg). This is converted to the actual condenser water approach
setpoint.
NOTE
The reset increment should be large enough for the system to register the reset
temperature and react to it – but not so large that it creates instability. If the
temperature increment is too small, the system won’t experience enough temperature
change to determine if it saves energy.
Adjust Reset Increments below: